The present study aims to identify effects due to convection heat transfer in a tube. Turbulent and laminar forced convection flow of a water-Al2O3 nanofluid in a tube subjected to a constant and uniform temperature at the wall was numerically analyzed. The single-phase model was employed to simulate the nanofluid convection, taking into account appropriate thermophysical properties. Particles are assumed spherical with a diameter equal to 24nm. Simulations have been carried out for the pertinent parameters in the following ranges: Reynolds number from 10(3) to 10(5) and volumetric fraction of alumina nanoparticles between 0 to 4%. It is found that convective heat transfer coefficient for nanofluids is greater than that of the base liquid. Heat transfer enhancement is increasing with the particle volume concentration and Reynolds number. As for the friction factor, it shows a good agreement with the classical correlation used for normal fluid, such as the Blasius formula. Moreover, a study on wall shear stress was attempted.